Study On The Melt Blending Modification Of Poly(Vinyl Chloride)

On the basis of consulting plenty of references about poly(vinyl chloride)(PVC) blending modification,surface function of carbon nanotubes(CNTs),ionic liquids and polymer matrix nanocomposites,two new ideas improving PVC by using the modified polyamide6(PA6)and carbon nanotube fluids are proposed.The main results can be summarized as follows:During the processes of PVC melt-blending modification by using PA6,firstly,the copolymer VM was synthesized by copolymerization of Vinyl Acetate and Maleic Anhydride.Then grafting copolymer VM-g-PA6 was obtained by melt blending of VM and PA6.Fourier transform infrared(FT-IR)spectroscopy demonstrated the successful grafting reaction of PA6 and VM.With the increasing amount of VM,the melting point of PA6 decreased gradually,and the minimum temperature fell down to 204℃.Blends of PVC and VM-g-PA6 were obtained by melt blending.Mechanical testing results of the blends showed that tensile strength increased with the increasing amount of VM-g-PA6,yet non-notched impact strength decreased at the same addition.Scanning Electron Microscopy(SEM)images showed that fracture mode of the blend samples were brittle fracture.Carbon nanotubes(CNTFs)were oxidized by using the mixture of concentrated sulfuric and nitric acids to introduce functional carbonyl and hydroxyl groups into the surface of CNTs.Subsequently,DC5700 and NPES reacted with the functional groups of the CNTs to yield a bilayer organic coating,namely the product of carbon nanotube fluids(CNTFs).The product was characterized by Fourier transform infrared(FT-IR), Thermo-gravimetric analysis(TGA),Differential scanning calorimeter(DSC)and Advanced Rheometric Expansion System(ARES)Rheometer.Results demonstrated successful chemical grafting of DC5700 and NPES into the CNTs structure and excellent fluidity of the CNTFs.The organic content of the CNTFs is about 84.8% with the remaining 15.2%attributed to CNTs.The nanocomposites of CNTFs/PVC were melting blended in a torque rheometer. The nanocomposites exhibit excellent mechanical properties attributed to addition of CNTFs.Compared to the tensile strength value 39.9MPa of neat PVC,it was improved up to 53.9MPa,which means about 35%increment.Meanwhile,the non-notched impact strength increased from 10.5MPa to the maximum value 14.8MPa,sum up to 40.6%.In addition,elongation also increased with the increasing amount of CNTFs.The rheological property of the composite was tested in a torque rheometer.After the addition of 5wt%CNTFs,the maximum torque decreased from 71N·m to 59.6N·m,and balanceable torque decreased from 35.6N·m to 30.1N·m. Results showed that CNTFs can be used as plasticizer of PVC.In a word,the CNTFs are excellent materials for plasticizing,reinforcing and toughening of PVC. Meanwhile,the CNTFs also increased the heat resistance properties of the composites and inhibited cross-linking of the resin effectively.